Inhibition of α-amylase activity by insoluble and soluble dietary fibers from kiwifruit (Actinidia deliciosa)

Effects of Kiwifruit Dietary Fibers on Pasting Properties and In Vitro Starch Digestibility of Wheat Starch

In this study, the roles of kiwifruit soluble/insoluble dietary fiber (SDF/IDF, respectively) in the pasting characteristics and in vitro digestibility of wheat starch were explored. According to RVA and rheological tests, the IDF enhanced the wheat starch viscosity, decreased the gelatinization degree of the starch granules, and exacerbated starch retrogradation. The addition of SDF in high quantities could reduce the starch gelatinization level, lower the system viscosity, and exacerbate starch retrogradation. Through determining the leached amylose content and conducing scanning electron microscopy, the IDF and SDF added in high quantities was combined with the leached amylose wrapped around the starch granules, which reduced the leached amylose content and decreased the gelatinization degree of the starch granules. The Fourier transform infrared results showed that the addition of both the IDF and SDF resulted in an enhancement in hydrogen bonding formed by the hydroxyl groups of the system. The in vitro digestion results strongly suggested that both the IDF and SDF reduced the wheat starch digestibility. The above findings are instructive for the application of both IDF and SDF in starchy functional foods.

Antioxidant, Antiglaucoma, Anticholinergic, and Antidiabetic Effects of Kiwifruit (Actinidia deliciosa) Oil: Metabolite Profile Analysis Using LC-HR/MS, GC/MS and GC-FID

Determining the antioxidant abilities and enzyme inhibition profiles of medicinally important plants and their oils is of great importance for a healthy life and the treatment of some common global diseases. Kiwifruit (Actinidia deliciosa) oil was examined and researched using several bioanalytical methods comprehensively for the first time in this research to determine its antioxidant, antiglaucoma, antidiabetic and anti-Alzheimer's capabilities. Additionally, the kiwifruit oil inhibitory effects on acetylcholinesterase (AChE), carbonic anhydrase II (CA II), and α-amylase, which are linked to a number of metabolic illnesses, were established. Furthermore, LC-HRMS analysis was used to assess the phenolic content of kiwifruit oil. It came to light that kiwifruit oil contained 26 different phenolic compounds. According to the LC-HRMS findings, kiwifruit oil is abundant in apigenin (74.24 mg/L oil), epigallocatechin (12.89 mg/L oil), caryophyllene oxide (12.89 mg/L oil), and luteolin (5.49 mg/L oil). In addition, GC-MS and GC-FID studies were used to ascertain the quantity and chemical composition of the essential oils contained in kiwifruit oil. Squalene (53.04%), linoleoyl chloride (20.28%), linoleic acid (2.67%), and palmitic acid (1.54%) were the most abundant compounds in kiwifruit oil. For radical scavenging activities of kiwifruit oil, 1,1-diphenyl-2-picryl-hydrazil (DPPH•) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS•+) radicals scavenging techniques were examined. These methods effectively demonstrated the potent radical scavenging properties of kiwifruit oil (IC50: 48.55 μg/mL for DPPH•, and IC50: 77.00 μg/mL for ABTS•+ scavenging). Also, for reducing capabilities, iron (Fe3+), copper (Cu2+), and Fe3+-2,4,6-tri(2-pyridyl)-S-triazine (TPTZ) reducing abilities were studied. Moreover, kiwifruit oil showed a considerable inhibition effect towards hCA II (IC50: 505.83 μg/mL), AChE (IC50: 12.80 μg/mL), and α-amylase (IC50: 421.02 μg/mL). The results revealed that the use of kiwifruit oil in a pharmaceutical procedure has very important effects due to its antioxidant, anti-Alzheimer, antidiabetic, and antiglaucoma effects.

Insoluble dietary fiber from wheat bran retards starch digestion by reducing the activity of alpha-amylase

This study investigated effects of insoluble dietary fiber (IDF) from wheat bran on starch digestion in vitro, analyzed the inhibition kinetics of IDF toward α-amylase and discussed the underlying mechanisms. Digestion results showed IDF significantly retarded starch digestion with reduced digestion rate and digestible starch content. Enzyme inhibition kinetics indicated IDF was a mixed-type inhibitor to α-amylase, because IDF could bind α-amylase, as evidenced by confocal laser scanning microscopy. Fluorescence quenching and UV-vis absorption experiments conformed this, found IDF led to static fluorescence quenching of α-amylase, mainly through van der Waals and/or hydrogen bonding forces. This interaction induced alternations in α-amylase secondary structure, showing more loosening and misfolding structures. This may prevent the active site of enzyme from capturing substrates, contributing to reduced α-amylase activity. These results would shed light on the utilization of IDF in functional foods for the management of postprandial blood glucose.

Recent trends of 3D printing based on starch-hydrocolloid in food, biomedicine and environment

People are exploring the potential application of 3D printing in food, biomedicine and environment, but it is urgent to find suitable bio-ink. Bio-ink compounded with starch and hydrocolloid can not only improve the rheology, structure and printability of starch-based edible bio-ink, but also endow it with other functional characteristics, so that it can be applied to food, biomedicine and even the environment, and meet the strategic needs of national health, green and sustainable development. In this paper, hydrocolloids are reviewed as potential means to regulate the physicochemical properties of starch, which endows it with good printability and presents excellent printing products. The specific applications of the bio-ink in the fields of food, biomedicine and environment in hypoglycemic, lipid-lowering, swallowable food, delivery, intelligent materials, and bio-sensor are also discussed. Then, the challenges and future development trends of realizing large-scale application are prospected. Proper physicochemical properties of starch-hydrocolloid are positively correlated with printability. The presentation of excellent printability has realized the application in different fields, not only satisfies most people, but also create benefits for some specific people. This review is expected to provide some theoretical guidance for the further development of 3D printing technology and its large-scale application.

Factors influencing the starch digestibility of starchy foods: A review

Starchy foods are a major energy source of the human diet, their digestion is closely related to human health. Most foods require lots of processing before eating, therefore, many factors can influence starch digestibility. The factors that affect the digestibility of starches have been widely discussed previously, but the extracted starches in those studies were different from those present within the actual food matrix. This review summarizes the factors influencing the starch digestibility in starchy foods. Endogenous non-starch components hinder the starch digestive process. Food ingredients and additives decrease starch digestibility by inhibiting the activity of digestive enzymes or hindering the contact between starch and enzymes. Storage induce the retrogradation of starch, decreasing the digestibility of foods. Therefore, preparing starchy foods with whole grains, processing them as little as possible, using food additives reasonably, and storage conditions may all be beneficial measures for the production of low GI foods.

Improving the function of pickle insoluble dietary fiber by coupling enzymatic hydrolysis with HHP treatment

In order to improve the function of insoluble dietary fiber (IDF) extracted from pickle, the coupled enzymatic hydrolysis and high hydrostatic pressure treatment method (EHHP) was used to modify its structure. Compared with the unmodified IDF (U-IDF), analysis of the particle size dispersion, bulk density, surface structure monosaccharide composition, microstructure, thermodynamic properties showed that the modified IDF (EHHP-IDF) has a looser and more porous structure, reduced particle size, bulk density, crystal strength and thermal stability, and increased xylose and galactose content. Due to the special looser microstructure, EHHP-IDF has showed the notable capacity of absorption of oil, glucose, nitrite, cholesterol as well as Pb2+. Collectively, these results show that EHHP has good potential use as an ideal modification method to improve the function of IDF, and a novel functional ingredient of EHHP-IDF which could be used in future food processing was obtained in this study.

Assisted Extraction with Cyclodextrins as a Way of Improving the Antidiabetic Activity of Actinidia Leaves

Five varieties of Actinidia leaves (Geneva, Jumbo, Ken's Red, Kijivska Hibridna, and Sentyabraskaya) were analyzed. The profiles of active compounds were determined, namely quercetin, rutin, epicatechin, chlorogenic acid, and kaempferol, in the raw material. Suspecting that the raw material might prove important in the treatment of diabetes, the authors assessed the antioxidant activity and the ability to inhibit enzymes responsible for the development of diabetes (α-glucosidase and α-amylase). As a result of the conducted analysis, the Ken's Red variety was indicated as having the highest biological activity (DPPH IC₅₀ = 0.332 ± 0.048; FRAP IC_0.5 = 0.064 ± 0.005; α-glucosidase inhibition IC₅₀ = 0.098 ± 0.007; α-amylase inhibition IC₅₀ = 0.083 ± 0.004). In order to increase the efficiency of the extraction of active compounds from Ken's Red variety leaves, cyclodextrins (α-CD, β-CD, and γ-CD) were used as extraction process enhancers. The obtained results showed a significant increase in the contents of extracted active compounds. In addition, the type of CD used enhanced the extraction of selected compounds (quercetin, kaempferol, rutin, chlorogenic acid, and epicatechin. This study shows that the application of cyclodextrin-based extraction significantly improved the leaf activity of the Ken's Red variety (DPPH IC₅₀ = 0.160 ± 0.019; FRAP IC_0.5 = 0.008 ± 0.001; α-glucosidase inhibition IC₅₀ = 0.040 ± 0.002; α-amylase inhibition IC₅₀ = 0.012 ± 0.003).

Structural changes and molecular mechanism study on the inhibitory activity of epigallocatechin against α-glucosidase and α-amylase

In this study, the inhibition and mechanism of epigallocatechin (EGC) on two key glycoside hydrolases (α-glucosidase, α-amylase) were explored from the molecular structure level. The chemical structure of EGC was characterized by X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and proton nuclear magnetic resonance spectroscopy. EGC's inhibition on these enzymes was colorimetrically determined. The effects of EGC on the chemical structure and spatial configuration of the enzymes were explored via FTIR spectroscopy, fluorescence spectroscopy, and molecular docking techniques. The results showed that EGC exhibited the inhibition of α-glucosidase and α-amylase in a non-competitive manner, showing a continuous upward trend as EGC's concentration increased. There was a fluorescence quenching effect of EGC on α-glucosidase and α-amylase. Molecular docking confirmed that EGC can bind to amino acid residues in the enzyme through intermolecular hydrogen bonds and hydrophobic interactions, resulting in the changed chemical structure and spatial conformation of the enzymes. This decreased enzyme activity. This result suggested that EGC has the potential to inhibit two key glycoside hydrolases, and it would be beneficial to incorporate EGC into functional foods for diabetics.

Acute effect of Melon Manis Terengganu peel powder on glycemic response, perceived satiety, and food intake: a randomized, placebo-controlled crossover trial in adults at risk of type 2 diabetes

BACKGROUND

Melon Manis Terengganu (MMT) peel has a high dietary fiber content, but there is no data examining its health benefits in adults at risk of type 2 diabetes. The objective of the study was to evaluate whether consumption of MMT peel powder improves glycemic response, satiety, and food intake in adults at risk of type 2 diabetes.

METHODS

An open-label, randomized, placebo-controlled, crossover design trial was conducted among adults (n = 30, ages 18-59 y) at risk of type 2 diabetes. They consumed Formulation 3 (formulated MMT peel powder) [A] and control (glucose) [B] with study breakfast based on randomly assigned treatment sequences (AB, BA) established by Research Randomizer ( www.randomizer.org ). Capillary blood glucose and perceived satiety were determined at baseline (0 min), 30, 60, 90 and 120 min, followed by a post-intervention food intake measurement.

RESULTS

The repeated measures analysis of variance (ANOVA) revealed significant time (F = 84.37, p <  0.001, η_p² = 0.744), condition (F = 22.89, p <  0.001, η_p² = 0.441), and time*condition effects (F = 24.40, p <  0.001, η_p² = 0.457) in blood glucose levels. Respondents (n = 30) who consumed Formulation 3 also had a significantly lower blood glucose 2-hour incremental area under the curve (iAUC) of 134.65 ± 44.51 mmol/L*min and maximum concentration (CMax) of 7.20 (7.10, 8.20) mmol/L with relative reduction of 26.8 and 13.3% respectively, when compared with control (p <  0.001). Besides, significantly greater perceived satiety, lower energy and fat intake as well as higher dietary fiber intake were also observed in the intervention group compared with the placebo group (p <  0.05). There were no marked side effects associated with the ingestion of the test products.

CONCLUSIONS

Short-term consumption of formulated MMT peel powder may improve glycemic response, increase perceived satiety and reduce food intake in adults at risk of type 2 diabetes with the potential to be utilized as a functional beverage. Medium-to long-term clinical trial is warranted to determine whether taking this formulated MMT peel powder on a daily basis has an influence on health outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05298111. Registered 28/03/2022.

Effects of Ball Milling Combined With Cellulase Treatment on Physicochemical Properties and in vitro Hypoglycemic Ability of Sea Buckthorn Seed Meal Insoluble Dietary Fiber

To improve the rough texture and hypoglycemic ability of sea buckthorn insoluble dietary fiber (IDF), a novel combined modification method was developed in this study. The IDF was treated with ball milling and cellulase treatment to obtain co-modified insoluble dietary fiber (CIDF). The physicochemical and functional properties of IDF, milled insoluble dietary fiber (MIDF), and CIDF were studied. After treatments, MIDF had smaller particle sizes and a looser structure, and CIDF exhibited a wrinkled surface and sparse porous structure according to scanning electron microscopy (SEM) and X-ray diffraction. Compared to IDF, MIDF and CIDF showed improved water-holding, oil-binding, and swelling capacities, improved by 16.13, 14.29, and 15.38%, and 38.5, 22.2, and 25.0%, for MIDF and CIDF, respectively. The cation exchange ability of modified samples showed improvement as well. Treatments also changed the fluidity of MIDF and CIDF. Due to the smaller particles and increased stacking, the bulk density (BD) and angle of repose of MIDF improved by 33.3% and 4.1° compared to IDF, whereas CIDF had a looser structure and thus decreased by 7.1% and 13.3° with increased fluidity. Moreover, the modification also enhanced the effects of CIDF on glucose adsorption, glucose diffusion inhibition, starch digestion inhibition, starch pasting interference, and α-amylase activity inhibition. In summary, IDF modified by ball milling combined with cellulose treatment could be developed as a functional ingredient for regulating glucose content.